A semiconductor manufacturing apparatus that employs a vacuum chamber is generally used when manufacturing a semiconductor thin film on a substrate.
Such a semiconductor manufacturing apparatus generally includes a plurality of vacuum chambers with a processing function necessary for manufacturing the semiconductor device such as film growing, and a conveying mechanism for conveying the substrate to be performed with the semiconductor manufacturing process between a plurality of vacuum chambers.
An in-line type using a tray and a feeding type using a vacuum robot and a transfer chamber are known as the conveying mechanism.
In the in-line type, a method of holding the tray using a wheel or a bearing and applying driving force using a chain or a gear etc. and to convey the tray is known (see e.g., Japanese Laid-Open Patent Publication No. H02-207546).
In the feeding type, a method in which a transformer chamber for arranging the robot is provided, vacuum chambers are arranged with the transfer chamber at the center, and the substrate is conveyed with a fork and the like attached to the robot is known (see e.g., Japanese Laid-Open Patent Publication No. H11-222675).
The structure of the apparatus is complicating in the in-line type, since the method that is adopted uses wheel, bearing or the like to hold the tray.
For instance, when using a plurality of vacuum chambers, different vacuum chambers are used for the respective purpose such as a charging room, reaction room etc., and a movable portion is arranged even in the reaction room where high cleanliness is required, and the cleanliness is reduced.
Since the tray is held with the wheel, bearing or the like, the contacting portion with respect to the device main body is limited, and grounding of the tray becomes a problem when using a high frequency power supply and the like.
If heating is involved in the manufacturing step of the semiconductor device, a certain degree of clearance must be provided in consideration of thermal expansion caused by heating in order for the drive portion such as chain, toothed gear or the like to continue to appropriately function around the time of heating, but such clearance may possibly lower the conveyance precision.
Countermeasures have been proposed such as configuring the drive portion with a material of small thermal expansion or suppressing thermal expansion by cooling the drive portion, but the cost increases or the structure of the apparatus becomes complicating in either case.
Further, with regards to the positioning of the tray, a detector for accurately detecting the position of the tray, and an actuator or a driving device of high precision for stopping the tray at a predetermined position at satisfactory precision are required, which increases cost and complicates the structure of the apparatus.
In the case of the feeding type conveying method using the vacuum robot, the transformer chamber for installing the vacuum robot must be arranged, which leads to increase in the device installation area. Further, an image recognizing device or other positioning mechanisms must be used to perform positioning of the substrate to be conveyed, which increases the cost and complicates the structure of the apparatus.